This study evaluates if promotion of a normocaloric and balanced diet and of physical activity, through an individual- or group-based lifestyle intervention of 12 months, may affect anthropometric measurements and metabolic profile in obese children.

Obese children are at risk of metabolic and cardiovascular complications both during pediatric age and later and they often show components of metabolic syndrome, such as dyslipidemia, hypertension and disturbed glucose metabolism . These complications are strictly associated with insulin resistance/hyperinsulinemia which is one of the most important contributing factors to cardiovascular disease. The gold standard technique to determine whole-body insulin sensitivity, the hyperinsulinemic-euglycemic clamp, is expensive, invasive and requires considerable expertise to be performed. Therefore, several surrogate measures have been developed. Among these, the triglyceride-glucose index (TyG) is a useful indicator, providing an easily and widely available simple laboratory method as a surrogate to estimate insulin resistance in adult, children and adolescents. Other useful indicators of insulin resistance and insulin sensitivity are the homeostatic model assessment of insulin resistance (HOMA-IR) and the quantitative insulin sensitivity check (QUICK) index, respectively, while HOMA-β% is useful to evaluate pancreatic β-cell function.

Among cardiovascular complications, obesity-related atherogenic dyslipidemia is a risk factor for cardiovascular disease. In childhood, atherogenic dyslipidemia may be associated with structural and functional vascular changes, as increased carotid intima-media thickness and increased arterial stiffness. The atherogenic index of plasma (AIP) is a recognized valuable indicator of the size of pre- and anti-atherogenic lipoprotein particle and is considered a major predictive marker of atherosclerosis risk. Additionally, it might be more promising than other lipid variables in assessing cardiovascular risk.

Guidelines for treatment of childhood obesity recommend intensive lifestyle interventions, involving diet, physical activity and behavior change, in an age-appropriate manner. While it is recognized that these interventions could favorably influence some variables of metabolic profile of obese children, no study has reported accurate possible effect on triglyceride-glucose index and atherogenic index of plasma. Furthermore, pediatric obesity interventions may be group and/or individual-based. The group-based intervention requires less resources, children may benefit from a positive social environment, but the attention to individual needs is limited, which may weaken outcomes. On the other hand, the individual-based intervention allows to tailor dietary and physical counselling on individual's needs but is more expensive and requires greater resources.

The aims of the study are to establish in patients who undergone individual versus group based intervention:

1. Effect on adiposity measured by BMI-zScore
2. effect on gluco-insulin metabolism evaluated by homa-index
3. effect on lipid profile evaluated by aterogenic index (AIP)

Inclusion Criteria:

• Obesity confirmed by BMI z-score >2 according to WHO growth charts
• Age at recruitment ≥6 years
• weight at birth ≥2500 g and <4000 g
• gestational age 37-42 weeks
• single birth
• Caucasian ethny
• family residing in Milan or neighborhood (≤30 km)

Exclusion Criteria:

• Syndromic, organic and hormonal conditions besides obesity
• Age at recruitment <6 years
• Low birthweight (<2500 g), birthweight >4000 g
• Pre-term or post-term birth
• Twin delivery
• Other ethnies than Caucasian